This device relates to a gimbal camlock installation asembly and more particularly to a double gimbal camlock installation assembly ahving a screw-driven, expandable camlock mechanism capable of gripping the inside surface of a tubular member, such as anuclear reactor steam generator tube for effectuating the inspection and repair of steam generator tubes and tube sheets.
A nuclear reaction is a device for producing heat by the controlled fission of nuclear material such as uranium or plutonium-bearing compounds. The nuclear material is contained in a reactor core which is disposed in a sealed primary coolant piping loop. A primary fluid, such as water, flows in the primary coolant piping loop for cooling the reactor core. In addition to the primary coolant piping loop, the nuclear reactor further comprises a secondary coolant piping loop in which flows a secondary fluid such as water. Heat, due to the fissioning of the nuclear material in the reactor core, is transferred by conduction from the core to the primary fluid flowing in the primary coolant piping loop. The heat due to fission is then transferred by conduction to the secondary fludi by using a heat exchanger device commonly referred to in the art as a steam generator. As described presently, the steam generator is in heat transfer communication with the primary and secondary fluids flowing in the primary and secondary coolant piping loops respectively.
As mentioned above, the steam generator is a heat exchanger device which transfers heat from the primary coolant piping loop to the secondary coolant piping loop. Disposed in the typical steam generator are a plurality of vertical, inverted U-shaped steam generator tubes through which flows the primary fluid. In heat transfer communication with the exterior surfaces of the tubes is the secondary fluid. Heat is transferred by conduction from the primary fluid to the secondary fluid through each tube wall. The primary fluid is recirculated through the primary coolant piping loop while the secondary fluid is ultimately circulated to a heat sink thereby transferring heat from the primary fluid to the heat sink. Typcially, the plurality of tubes are connected to a plurality of steam generator tube support plates which are disposed in the steam generator at various locations along the length of the tubes for supporting the tubes and for reducing flow-induced vibration in the tubes. The ends of the tubes may be disposed in a plurality of vertical apertures that are formed in a tube sheet. Moreover, the primary fluid is radioactive; therefore, the steam generator is designed such that the primary fluid is nowhere in direct fluid communication with the secondary fluid.
Occasionally, it is necessary to inspect and repair the tubes or the tube sheet to maintain the complete separation of the primary and secondary fluids. A camlock apparatus may be utilized to effectuate such inspections and repairs. The camlock apparatus is installed in the end of a selected vertical steam generator host tube and an inspection or repair tool may be then attached to the camlock apparatus. The tool is used to inspect or repair a tube or tube sheet. Following the inspection or repair, the inspection or repair tool is detached from the camlock apparatus and the camlock apparatus is retrieved from the host tube. However, before the camlock apparatus may be installed in the host tube, it is preferred that the camlock apparatus first be vertically aligned with the host tube so that it may be efficiently installed in the host tube.
There are several devices known in the art for aligning and pivoting an element. One such device is disclosed by U.S. Pat. No. 4,451,198 issued May 29, 1984 in the name of Edward T. Sanderson and entitled "Material Handling Device". This patent discloses an attachment device for providing a gimbal-type pivoting arrangement whereby a coil of flat material, such as coiled steel, can be transported, picked up and released in either a horizontal or vertical plane. However, this attachment device is inappropriate for deployment in a typical steam generator to inspect or repair steam generator tubes or tube sheets because this attachment device allows pivoting of the element only in one arc for bringing the element to a vertical position. Therefore, this attachment device does not allow for pivoting in either of two mutually perpendicular arcs. Pivoting in either of two mutually perpendicular arcs is preferred when a camlock apparatus is used for inspecting or repairing steam generator tubes or tube sheets.
Another device known in the art that utilizes a gimbal-type device for aligning and rotating an element is disclosed by U.S. Pat. No. 2,188,793 issued Jan. 30, 1940 in the name of Thomas Jefferson Newbold and entitled "Heat Treating Device". This patent discloses a device having a holder for subjecting elements to heat of a fire or flame while held in the hand of the user at a point remote from the heat. This device provides a handle and material-holding mechanism connected therewith by means of a universally flexible joint, coupling, or connection, so that any desired side of the material-holder may be presented to the heat without change of the direction of the axis of the handle. However, this device is not capable of properly installing a camlock apparatus in a steam generator tube due at least in part to this device being rotatable only about the vertical axis of the flexible joint. Consequently, this device is not capable of pivoting in two mutually perpendicular arcs which is preferred when inspecting or repairing a steam generator tube or tube sheet.
A device typical of the art of expandable camlocks is disclosed by U.S. Pat. No. 4,427,317 issued Jan. 24, 1984 in the name of John J. Wilhelm and entitled "Expandable Camlock" which is assigned to the Westinghouse Electric Corporation. This device employs a camlock for engaging the inside of a tubular member and for suspending apparatus from the tubular member for inspecting or repairing a steam generator tube or tubesheet. However, this patent does not disclose the use of a gimbal-type device for vertically aligning the camlock with a host tube.
Consequently, while the prior art disclosed gimbal-type devices for aligning an element and disclosed devices for installing camlocks in steam generator tubes, the prior art did not disclose a device which combined a gimbal-type device and a camlock for effectuating the inspection or repair of steam generator tubes and tube sheets.
Therefore, what is needed is a double gimbal camlock installation assembly capable of pivoting in two mutually perpendicular arcs to vertically align and install a camlock apparatus in a steam generator tube for effectuating the inspection and repair of steam generator tubes and tube sheets.